Clinical and therapeutic features of myositis associated with anti-MDA5 antibodies: three new cases

Abstract

Abstract Purpose To assess clinical features, therapy, and outcome of the myositis associated with anti-MDA5 antibodies, and to propose a successful therapeutic protocol for rapidly progressive interstitial lung disease (RP-ILD) in anti-MDA5 dermatomyositis (DM). Methods A retrospective and descriptive study of three cases of anti-MDA5 associated myositis was conducted in the Department of Internal Medicine in the University Hospital Hedi Chaker, Sfax, Tunisia, between 1996 and 2016. Results From a series of 115 cases of myositis, three cases of anti-MDA5-positive DM were identified. They were three men with a mean age of 63 years. They manifested specific cutaneous manifestations including ulcers and palmar papules, mild muscular involvement, and RP-ILD. The severity of the disease was correlated to the ILD in all patients. Aggressive therapies were tried including high-dose corticoids, cyclophosphamide (CYC) cures, intravenous immunoglobulins, and rituximab (RTX), with a good outcome in the patient who received combined high steroids, CYC, and RTX pulses. The two other patients died because of a rapid worsening of their respiratory condition. Conclusion Anti-MDA positive myositis is characterised by a specific cutaneous phenotype, the discretion of muscular signs, and the correlation with RP-ILD. The poor prognosis of this entity is correlated to the high resistance of pulmonary involvement despite aggressive therapeutics. The combination between high-dose steroids, CYC, and RTX has shown good results in many reports, as well as in one of our patients.